TERRAFORMING TERRA
We discuss and comment on the role agriculture will play in the containment of the CO2 problem and address protocols for terraforming the planet Earth.
A model farm template is imagined as the central methodology. A broad range of timely science news and other topics of interest are commented on.

Thursday, December 22, 2011

Heavy Metal Removal Engineered Successfully

Effectively we combine the two
presently used methods and are able to nicely work them to good effect which is
impossible as separate systems. The real
question is whether this can all be done while making economic sense. There is a lot of system cycling going on and
that runs up the meter.

At least enough is now known that
feasibility seems to be real.

Of course, no one dares to
suggest producing the sludge and drying it out prior to putting it on a rail
car to the coast and simply dumping it offshore to achieve safe dilution back
into the ocean’s brine as a natural constituent. No one could ever patent that.

Almost all our waste management
problems could easily disappear by simply applying this procedure or some
circumscribed version of it. I induced a
bit of a row a couple of decades ago by having some friends suggest (half
seriously as it actually makes perfect rational sense) that a very large atoll
(the largest) in the Marshalls
would be perfect for the disposal of LA’s trash. The reaction was choice and beautifully
irrational.

It looks even better today as the
waste management industry is nicely running out of decent options and it
becomes possible to hoist progressively more expensive solutions onto the backs
of the poor ratepayers.

Novel Device Removes Heavy Metals from Water

ScienceDaily (Dec. 16, 2011) — Engineers at Brown University have
developed a system that cleanly and efficiently removes trace heavy metals from
water. In experiments, the researchers showed the system reduced cadmium,
copper, and nickel concentrations, returning contaminated water to near or
below federally acceptable standards. The technique is scalable and has viable
commercial applications, especially in the environmental remediation and metal
recovery fields.

An unfortunate consequence of many industrial and manufacturing
practices, from textile factories to metalworking operations, is the release of
heavy metals in waterways. Those metals can remain for decades, even centuries,
in low but still dangerous concentrations.

Ridding water of trace metals "is really hard to do," said
Joseph Calo, professor emeritus of engineering who maintains an
active laboratory at Brown. He noted the cost, inefficiency, and time needed
for such efforts. "It's like trying to put the genie back in the
bottle."

That may be changing. Calo and other engineers at Brown describe a
novel method that collates trace heavy metals in water by increasing their
concentration so that a proven metal-removal technique can take over. In a
series of experiments, the engineers report the method, called the cyclic
electrowinning/precipitation (CEP) system, removes up to 99 percent of copper,
cadmium, and nickel, returning the contaminated water to federally accepted
standards of cleanliness. The automated CEP system is scalable as well, Calo
said, so it has viable commercial potential, especially in the environmental
remediation and metal recovery fields. The system's mechanics and results are
described in a paper published in the Chemical Engineering Journal.

A proven technique for removing heavy metals from water is through the
reduction of heavy metal ions from an electrolyte. While the technique has
various names, such as electrowinning, electrolytic removal/recovery or
electroextraction, it all works the same way, by using an electrical current to
transform positively charged metal ions (cations) into a stable, solid state
where they can be easily separated from the water and removed.

The main drawback to this technique is that there must be a high-enough
concentration of metal cations in the water for it to be effective; if the
cation concentration is too low -- roughly less than 100 parts per million --
the current efficiency becomes too low and the current acts on more than the
heavy metal ions.

Another way to remove metals is through simple chemistry. The technique
involves using hydroxides and sulfides to precipitate the metal ions from the
water, so they form solids. The solids, however, constitute a toxic sludge, and
there is no good way to deal with it.

The dilemma, then, is how to remove the metals efficiently without
creating an unhealthy byproduct. Calo and his co-authors, postdoctoral
researcher Pengpeng Grimshaw and George Hradil, who earned his doctorate at
Brown and is now an adjunct professor, combined the two techniques to form a
closed-loop system. "We said, 'Let's use the attractive features of both
methods by combining them in a cyclic process,'" Calo said.

It took a few years to build and develop the system. In the paper, the
authors describe how it works. The CEP system involves two main units, one to
concentrate the cations and another to turn them into stable, solid-state metals
and remove them. In the first stage, the metal-laden water is fed into a tank
in which an acid (sulfuric acid) or base (sodium hydroxide) is added to change
the water's pH, effectively separating the water molecules from the metal
precipitate, which settles at the bottom. The "clear" water is siphoned
off, and more contaminated water is brought in. The pH swing is applied again,
first redissolving the precipitate and then reprecipitating all the metal,
increasing the metal concentration each time. This process is repeated until
the concentration of the metal cations in the solution has reached a point at
which electrowinning can be efficiently employed.

When that point is reached, the solution is sent to a second device,
called a spouted particulate electrode (SPE). This is where the electrowinning
takes place, and the metal cations are chemically changed to stable metal
solids so they can be easily removed. The engineers used an SPE developed by
Hradil, a senior research engineer at Technic Inc., located in Cranston, R.I.
The cleaner water is returned to the precipitation tank, where metal ions can
be precipitated once again. Further cleaned, the supernatant water is sent to
another reservoir, where additional processes may be employed to further lower
the metal ion concentration levels. These processes can be repeated in an
automated, cyclic fashion as many times as necessary to achieve the desired
performance, such as to federal drinking water standards.

In experiments, the engineers tested the CEP system with cadmium,
copper, and nickel, individually and with water containing all three metals.
The results showed cadmium, copper, and nickel were lowered to 1.50, 0.23 and
0.37 parts per million (ppm), respectively -- near or below maximum contaminant
levels established by the Environmental Protection Agency. The sludge is
continuously formed and redissolved within the system so that none is left as
an environmental contaminant.

"This approach produces very large volume reductions from the
original contaminated water by electrochemical reduction of the ions to
zero-valent metal on the surfaces of the cathodic particles," the authors
write. "For an initial 10 ppm ion concentration of the metals considered,
the volume reduction is on the order of 106."

Calo said the approach can be used for other heavy metals, such as
lead, mercury, and tin. The researchers are currently testing the system with
samples contaminated with heavy metals and other substances, such as sediment,
to confirm its operation.

The research was funded by the National Institute of Environmental
Health Sciences, a branch of the National Institutes of Health, through the BrownUniversity
Superfund Research Program.

Editors: BrownUniversity has a fiber
link television studio available for domestic and international live and taped
interviews, and maintains an ISDN line for radio interviews. For more
information, call (401) 863-2476.

No comments:

About Me

Apr 2017 - 4.1 Mil Pg Views, March 2013 - Posted my paper introducing CLOUD COSMOLOGY & NEUTRAL NEUTRINO rigorously described, September 2010 I am pleased to report that my essay titled A NEW METRIC WITH APPLICATIONS TO PHYSICS AND SOLVING CERTAIN HIGHER ORDERED DIFFERENTIAL EQUATIONS' has been published in Physics Essays(AIP) and appeared in their June 2010 quarterly. 40 years ago I took an honors degree in applied mathematics from the University of Waterloo. My interest was Relativity and my last year there saw me complete a 900 level course under Hanno Rund on his work in relativity,as well as differential geometry(pure math) and of course analysis. I continued researching new ideas and knowledge since that time and I have prepared a book for publication titled Paradigms Shift&. I maintain my blog as a day book and research tool to retain data and record impressions and interpretations on material read. Do join my blog and receive Four items of interest daily Monday through Saturday.